Write the null and alternative hypotheses for each of the following examples. Determine if each is a case of a two-tailed, a left-tailed, and a right-tailed test.
a. To test if the mean amount of time spent per week watching sports on television by all adult men is different from 9.5 hours.
b. To test if the mean amount of money spent by all customers at a supermarket is less than $105.
c. To test whether the mean starting salary of college graduates is higher than $39000 per year.
d. To test if the mean waiting time at the drive-through window at a fast food restaurant during rush hour differs from 10 minutes.
Question 4:
The daily production rates for a sample of factory workers before and after a training program are shown below. Let d = After - Before.
Worker Before After
1 6 9
2 10 12
3 9 10
4 8 11
5 7 9
We want to determine if the training program was effective.
a. Give the hypotheses for this problem.
b. Compute the test statistic.
c. At 95% confidence, test the hypotheses. That is, did the training program actually
increase the production rates?
Question 5:
The heating bills for a selected sample of houses using various forms of heating are given below. (Values are in dollars.)
Natural Gas Central Electric Heat Pump
84 95 85
64 60 93
93 89 90
88 96 92
71 90 80
a. At ? = 0.05, test to see if there is a significant difference among the average heating bills of the homes. Use the p-value approach.
b. Test the above hypotheses using the critical value approach. Let ? = .05.